Averaging water content and electrical conductivity of a layered soil using time domain reflectmetry Hiroyuki Ochiai, and Kosuke Noborio School of Agriculture,

Averaging water content and electrical conductivity of a layered soil using time domain reflectmetry

Hiroyuki Ochiai, and Kosuke Noborio

School of Agriculture, Meiji University, Japan

People use TDR probes vertically and horizontally People use TDR probes vertically and horizontally installed.installed. 　　 However there is a little of research on However there is a little of research on vertical TDR probes taking an average of vertical TDR probes taking an average of water content () and and electrical　 conductivity (EC) with layers. In EC) with layers. In this study, averaging EC is shown.this study, averaging EC is shown.

Objective

・ Topp et al. (1980, 1982) developed the Time Domain Reflectmetry (TDR) method for measuring soil water content ().

・ Topp and Davis (1984) studied measuring q at the field by TDR.

・ Kachanoski et al. (1990) were using TDR probes by vertically insert.

・ Nadler et al. (1991) studied measuring electrical 　 conductivity by TDR method.

Background

Material

TDR probe for vertical(80mm)

80mm80mm

Column with TDR probeColumn with TDR probe

i.d.=76.5mm h=20mm

Research

Type1. Same water content and different concentration in each columns

Type2. Different water content and same concentration in each columns

Type3. Different water content and different concentration in each columns

Steady Water Content and Different Concentration

0 20 40 60 80

1

2

3

4

5

EC(S/ m)

vertical averagehorizontal averate

Results and Discussion

Type1

1. Similar concentration in 3yayers1. Similar concentration in 3yayers

vertical = horizontalvertical = horizontal

2. Highest concentration in the highest column2. Highest concentration in the highest column

vertical > horizontalvertical > horizontal

3. Highest concentration in the lowest column3. Highest concentration in the lowest column


4. Lowest concentration in the middle column4. Lowest concentration in the middle column


5. Highest concentration in the middle column 5. Highest concentration in the middle column

vertical < horizontalvertical < horizontal

Type2

Dfferent Water Content and Steady Concentration

0 20 40 60 80

6

7

8

9

10

EC(S/m) vertical averagehorizontal average

6. Similar 6. Similar in 3yayers in 3yayers

vertical = horizontalvertical = horizontal

7. Highest 7. Highest in the middle column in the middle column


8. Highest 8. Highest in the highest column and middle is the lowest in the highest column and middle is the lowest


9. Highest 9. Highest in the lowest column and middle is the lowest in the lowest column and middle is the lowest


10. higher 10. higher in the higher column in the higher column


Type1

Type2

Type3

Type311. Highest concentration in the highest column and the highest 11. Highest concentration in the highest column and the highest

in the middle columnin the middle column


12. Highest concentration in the highest column and the highest 12. Highest concentration in the highest column and the highest in the lowest columnin the lowest column


13. Highest concentration in the lowest column and the highest 13. Highest concentration in the lowest column and the highest in the highest columnin the highest column


14. Highest concentration in the lowest column and the lowest 14. Highest concentration in the lowest column and the lowest in in the highest columnthe highest column


15. Highest concentration in the lowest column and the lowest 15. Highest concentration in the lowest column and the lowest in in the middle columnthe middle column


16. Highest concentration in the middle column and the lowest 16. Highest concentration in the middle column and the lowest in the lowest columnin the lowest column


17. Highest concentration in the middle column and the lowest 17. Highest concentration in the middle column and the lowest in the middle columnin the middle column


Conclusions

Average data of Average data of vertical probesvertical probes

Average data of Average data of horizontal probeshorizontal probes

==

・・ When mass of KCl in the top or bottom column is the highesWhen mass of KCl in the top or bottom column is the highest,t,Average data of Average data of

vertical probesvertical probesAverage data of Average data of

horizontal probeshorizontal probes>>



>>

・・ When mass of KCl in the middle column is the lowest,When mass of KCl in the middle column is the lowest,

・・ When mass of KCl in the middle column is the highest,When mass of KCl in the middle column is the highest,

・・ When mass of KCl in 3 columns is the same,When mass of KCl in 3 columns is the same,



<<

Note

Win TDR sometimes did not work because the form between t1 and t2 is wavy. Therefore, it did not proceed to obtain an EC value.

- 0.20

- 0.10

0.00

0.10

0.20

0.30

0.40

0.50

t1t1 t2t2

Different Water Content and Different Concentration

0 20 40 60 80

11

12

13

14

15

16

17

EC(S/ m)

vertical averagehorizontal average

・・ Ratio differences of mass KCl in each columns effect on incrRatio differences of mass KCl in each columns effect on increasing differences of average data between vertically and easing differences of average data between vertically and horizontally.horizontally.

acknowledgement

This study is carried out as a part of “Ground – based Research Announcement for Space Utilization” promoted by Japan Space Forum

Documents

Averaging water content and electrical conductivity of a layered soil using time domain reflectmetry Hiroyuki Ochiai, and Kosuke Noborio School of Agriculture,